Epson ES-1200C - Manual (Page 22)

SCSI ID number setting
The factory set SCSI ID of the scanner is 2. The computer is
usually ID number 7. If you are going to add the scanner to a
system in which one of your SCSI devices already has a SCSI
ID of 2, change the ID number of the scanner to an unused
number as described next.
1. Locate the SCSI ID rotary switch on the rear panel of the
scanner.
2. To change the SCSI ID, turn the small dial to the desired
number.
Caution:
Do not set the SCSI ID to an ID number that is already
assigned to another device. The computer, scanner, and other
devices will not function properly.
Setting Up the Scanner 1-9